gdb: update 11.1 -> 11.2

Simplyfy .inc structure: merge gdb.inc into gdb_11.2.bb, rename
gdb-${PV}.inc to gdb.inc. This will allow easier automatic updates.

Drop upstreamed patch.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>